This proposal is to continue research on the mechanisms of human allergic reactions. A basic premise is that the IgE-mediated release of mediators from basophils and mast cells contributes substantially to these disease processes; and, further, that some aspects of these reactions are too complex for in vivo analysis. We have developed several in vitro systems for these studies. One is immunochemical, designed to elicit a precise definition of the quantity and characteristics of the IgE antibodies which are involved in allergic disorders. This will allow us to understand the distribution of allergen after human exposure. Another approach involves detailed studies of the release of histamine and other mediators from human basophils; we will examine the role of cyclic nucleotides in the release processes and the changes which result from agonist or hormone receptor interactions. The role of arachidonic acid metabolism in both the release process and its pharmacologic control will also be studied. In collaboration with Drs. Dembo and Goldstein, we will continue mathematical modeling of the release and desensitization of antigen-stimulated basophils; the desensitization process will also be probed by immunochemical and biochemical studies. Studies on the nature and effects of the released mediators will be continued, concentrating on the role of SRS-A and the newly defined mediators which act on the Hageman Factor dependent kinin-generating pathways. We will attempt to isolate the molecules which generate kinin from high molecular weight kininogen and which cleave and activate Hageman Factor and to study the nature of their interaction with the serum cascade systems. Finally, studies of allergen chemistry will involve definition of the allergens in vespid venoms, the potential usefulness of derivatized antigens and an analysis of allergenic fragments with haptenic (inhibitory) properties.